text: /*
   * Copyright (C) 2010 Georg Martius <georg.martius@web.de>
   * Copyright (C) 2010 Daniel G. Taylor <dan@programmer-art.org>
   *
   * This file is part of FFmpeg.
   *
   * FFmpeg is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * FFmpeg is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with FFmpeg; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  /**
   * @file
   * fast deshake / depan video filter
   *
   * SAD block-matching motion compensation to fix small changes in
   * horizontal and/or vertical shift. This filter helps remove camera shake
   * from hand-holding a camera, bumping a tripod, moving on a vehicle, etc.
   *
   * Algorithm:
   *   - For each frame with one previous reference frame
   *       - For each block in the frame
   *           - If contrast > threshold then find likely motion vector
   *       - For all found motion vectors
   *           - Find most common, store as global motion vector
   *       - Find most likely rotation angle
   *       - Transform image along global motion
   *
   * TODO:
   *   - Fill frame edges based on previous/next reference frames
   *   - Fill frame edges by stretching image near the edges?
   *       - Can this be done quickly and look decent?
   *
   * Dark Shikari links to http://wiki.videolan.org/SoC_x264_2010#GPU_Motion_Estimation_2
   * for an algorithm similar to what could be used here to get the gmv
   * It requires only a couple diamond searches + fast downscaling
   *
   * Special thanks to Jason Kotenko for his help with the algorithm and my
   * inability to see simple errors in C code.
   */
  
  #include "avfilter.h"
  #include "libavutil/common.h"
  #include "libavutil/mem.h"
  #include "libavutil/pixdesc.h"
  #include "libavcodec/dsputil.h"
  
  #include "transform.h"
  
  #define CHROMA_WIDTH(link)  -((-link->w) >> av_pix_fmt_descriptors[link->format].log2_chroma_w)
  #define CHROMA_HEIGHT(link) -((-link->h) >> av_pix_fmt_descriptors[link->format].log2_chroma_h)
  
  enum SearchMethod {
      EXHAUSTIVE,        ///< Search all possible positions
      SMART_EXHAUSTIVE,  ///< Search most possible positions (faster)
      SEARCH_COUNT
  };
  
  typedef struct {
      int x;             ///< Horizontal shift
      int y;             ///< Vertical shift
  } IntMotionVector;
  
  typedef struct {
      double x;             ///< Horizontal shift
      double y;             ///< Vertical shift
  } MotionVector;
  
  typedef struct {
      MotionVector vector;  ///< Motion vector
      double angle;         ///< Angle of rotation
      double zoom;          ///< Zoom percentage
  } Transform;
  
  typedef struct {
      AVClass av_class;
      AVFilterBufferRef *ref;    ///< Previous frame
      int rx;                    ///< Maximum horizontal shift
      int ry;                    ///< Maximum vertical shift
      enum FillMethod edge;      ///< Edge fill method
      int blocksize;             ///< Size of blocks to compare
      int contrast;              ///< Contrast threshold
      enum SearchMethod search;  ///< Motion search method
      AVCodecContext *avctx;
      DSPContext c;              ///< Context providing optimized SAD methods
      Transform last;            ///< Transform from last frame
      int refcount;              ///< Number of reference frames (defines averaging window)
      FILE *fp;
      Transform avg;
      int cw;                    ///< Crop motion search to this box
      int ch;
      int cx;
      int cy;
  } DeshakeContext;
  
  static int cmp(const double *a, const double *b)
  {
      return *a < *b ? -1 : ( *a > *b ? 1 : 0 );
  }
  
  /**
   * Cleaned mean (cuts off 20% of values to remove outliers and then averages)
   */
  static double clean_mean(double *values, int count)
  {
      double mean = 0;
      int cut = count / 5;
      int x;
  
      qsort(values, count, sizeof(double), (void*)cmp);
  
      for (x = cut; x < count - cut; x++) {
          mean += values[x];
      }
  
      return mean / (count - cut * 2);
  }
  
  /**
   * Find the most likely shift in motion between two frames for a given
   * macroblock. Test each block against several shifts given by the rx
   * and ry attributes. Searches using a simple matrix of those shifts and
   * chooses the most likely shift by the smallest difference in blocks.
   */
  static void find_block_motion(DeshakeContext *deshake, uint8_t *src1,
                                uint8_t *src2, int cx, int cy, int stride,
                                IntMotionVector *mv)
  {
      int x, y;
      int diff;
      int smallest = INT_MAX;
      int tmp, tmp2;
  
      #define CMP(i, j) deshake->c.sad[0](deshake, src1 + cy * stride + cx, \
                                          src2 + (j) * stride + (i), stride, \
                                          deshake->blocksize)
  
      if (deshake->search == EXHAUSTIVE) {
          // Compare every possible position - this is sloooow!
          for (y = -deshake->ry; y <= deshake->ry; y++) {
              for (x = -deshake->rx; x <= deshake->rx; x++) {
                  diff = CMP(cx - x, cy - y);
                  if (diff < smallest) {
                      smallest = diff;
                      mv->x = x;
                      mv->y = y;
                  }
              }
          }
      } else if (deshake->search == SMART_EXHAUSTIVE) {
          // Compare every other possible position and find the best match
          for (y = -deshake->ry + 1; y < deshake->ry - 2; y += 2) {
              for (x = -deshake->rx + 1; x < deshake->rx - 2; x += 2) {
                  diff = CMP(cx - x, cy - y);
                  if (diff < smallest) {
                      smallest = diff;
                      mv->x = x;
                      mv->y = y;
                  }
              }
          }
  
          // Hone in on the specific best match around the match we found above
          tmp = mv->x;
          tmp2 = mv->y;
  
          for (y = tmp2 - 1; y <= tmp2 + 1; y++) {
              for (x = tmp - 1; x <= tmp + 1; x++) {
                  if (x == tmp && y == tmp2)
                      continue;
  
                  diff = CMP(cx - x, cy - y);
                  if (diff < smallest) {
                      smallest = diff;
                      mv->x = x;
                      mv->y = y;
                  }
              }
          }
      }
  
      if (smallest > 512) {
          mv->x = -1;
          mv->y = -1;
      }
      emms_c();
      //av_log(NULL, AV_LOG_ERROR, "%d\n", smallest);
      //av_log(NULL, AV_LOG_ERROR, "Final: (%d, %d) = %d x %d\n", cx, cy, mv->x, mv->y);
  }
  
  /**
   * Find the contrast of a given block. When searching for global motion we
   * really only care about the high contrast blocks, so using this method we
   * can actually skip blocks we don't care much about.
   */
  static int block_contrast(uint8_t *src, int x, int y, int stride, int blocksize)
  {
      int highest = 0;
      int lowest = 0;
      int i, j, pos;
  
      for (i = 0; i <= blocksize * 2; i++) {
          // We use a width of 16 here to match the libavcodec sad functions
          for (j = 0; i <= 15; i++) {
              pos = (y - i) * stride + (x - j);
              if (src[pos] < lowest)
                  lowest = src[pos];
              else if (src[pos] > highest) {
                  highest = src[pos];
              }
          }
      }
  
      return highest - lowest;
  }
  
  /**
   * Find the rotation for a given block.
   */
  static double block_angle(int x, int y, int cx, int cy, IntMotionVector *shift)
  {
      double a1, a2, diff;
  
      a1 = atan2(y - cy, x - cx);
      a2 = atan2(y - cy + shift->y, x - cx + shift->x);
  
      diff = a2 - a1;
  
      return (diff > M_PI)  ? diff - 2 * M_PI :
             (diff < -M_PI) ? diff + 2 * M_PI :
             diff;
  }
  
  /**
   * Find the estimated global motion for a scene given the most likely shift
   * for each block in the frame. The global motion is estimated to be the
   * same as the motion from most blocks in the frame, so if most blocks
   * move one pixel to the right and two pixels down, this would yield a
   * motion vector (1, -2).
   */
  static void find_motion(DeshakeContext *deshake, uint8_t *src1, uint8_t *src2,
                          int width, int height, int stride, Transform *t)
  {
      int x, y;
      IntMotionVector mv = {0, 0};
      int counts[128][128];
      int count_max_value = 0;
      int contrast;
  
      int pos;
      double *angles = av_malloc(sizeof(*angles) * width * height / (16 * deshake->blocksize));
      int center_x = 0, center_y = 0;
      double p_x, p_y;
  
      // Reset counts to zero
      for (x = 0; x < deshake->rx * 2 + 1; x++) {
          for (y = 0; y < deshake->ry * 2 + 1; y++) {
              counts[x][y] = 0;
          }
      }
  
      pos = 0;
      // Find motion for every block and store the motion vector in the counts
      for (y = deshake->ry; y < height - deshake->ry - (deshake->blocksize * 2); y += deshake->blocksize * 2) {
          // We use a width of 16 here to match the libavcodec sad functions
          for (x = deshake->rx; x < width - deshake->rx - 16; x += 16) {
              // If the contrast is too low, just skip this block as it probably
              // won't be very useful to us.
              contrast = block_contrast(src2, x, y, stride, deshake->blocksize);
              if (contrast > deshake->contrast) {
                  //av_log(NULL, AV_LOG_ERROR, "%d\n", contrast);
                  find_block_motion(deshake, src1, src2, x, y, stride, &mv);
                  if (mv.x != -1 && mv.y != -1) {
                      counts[mv.x + deshake->rx][mv.y + deshake->ry] += 1;
                      if (x > deshake->rx && y > deshake->ry)
                          angles[pos++] = block_angle(x, y, 0, 0, &mv);
  
                      center_x += mv.x;
                      center_y += mv.y;
                  }
              }
          }
      }
  
      if (pos) {
           center_x /= pos;
           center_y /= pos;
           t->angle = clean_mean(angles, pos);
           if (t->angle < 0.001)
                t->angle = 0;
      } else {
           t->angle = 0;
      }
  
      // Find the most common motion vector in the frame and use it as the gmv
      for (y = deshake->ry * 2; y >= 0; y--) {
          for (x = 0; x < deshake->rx * 2 + 1; x++) {
              //av_log(NULL, AV_LOG_ERROR, "%5d ", counts[x][y]);
              if (counts[x][y] > count_max_value) {
                  t->vector.x = x - deshake->rx;
                  t->vector.y = y - deshake->ry;
                  count_max_value = counts[x][y];
              }
          }
          //av_log(NULL, AV_LOG_ERROR, "\n");
      }
  
      p_x = (center_x - width / 2);
      p_y = (center_y - height / 2);
      t->vector.x += (cos(t->angle)-1)*p_x  - sin(t->angle)*p_y;
      t->vector.y += sin(t->angle)*p_x  + (cos(t->angle)-1)*p_y;
  
      // Clamp max shift & rotation?
      t->vector.x = av_clipf(t->vector.x, -deshake->rx * 2, deshake->rx * 2);
      t->vector.y = av_clipf(t->vector.y, -deshake->ry * 2, deshake->ry * 2);
      t->angle = av_clipf(t->angle, -0.1, 0.1);
  
      //av_log(NULL, AV_LOG_ERROR, "%d x %d\n", avg->x, avg->y);
      av_free(angles);
  }
  
  static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
  {
      DeshakeContext *deshake = ctx->priv;
      char filename[256] = {0};
  
      deshake->rx = 16;
      deshake->ry = 16;
      deshake->edge = FILL_MIRROR;
      deshake->blocksize = 8;
      deshake->contrast = 125;
      deshake->search = EXHAUSTIVE;
      deshake->refcount = 20;
  
      deshake->cw = -1;
      deshake->ch = -1;
      deshake->cx = -1;
      deshake->cy = -1;
  
      if (args) {
          sscanf(args, "%d:%d:%d:%d:%d:%d:%d:%d:%d:%d:%255s",
                 &deshake->cx, &deshake->cy, &deshake->cw, &deshake->ch,
                 &deshake->rx, &deshake->ry, (int *)&deshake->edge,
                 &deshake->blocksize, &deshake->contrast, (int *)&deshake->search, filename);
  
          deshake->blocksize /= 2;
  
          deshake->rx = av_clip(deshake->rx, 0, 64);
          deshake->ry = av_clip(deshake->ry, 0, 64);
          deshake->edge = av_clip(deshake->edge, FILL_BLANK, FILL_COUNT - 1);
          deshake->blocksize = av_clip(deshake->blocksize, 4, 128);
          deshake->contrast = av_clip(deshake->contrast, 1, 255);
          deshake->search = av_clip(deshake->search, EXHAUSTIVE, SEARCH_COUNT - 1);
  
      }
      if (*filename)
          deshake->fp = fopen(filename, "w");
      if (deshake->fp)
          fwrite("Ori x, Avg x, Fin x, Ori y, Avg y, Fin y, Ori angle, Avg angle, Fin angle, Ori zoom, Avg zoom, Fin zoom\n", sizeof(char), 104, deshake->fp);
  
      // Quadword align left edge of box for MMX code, adjust width if necessary
      // to keep right margin
      if (deshake->cx > 0) {
          deshake->cw += deshake->cx - (deshake->cx & ~15);
          deshake->cx &= ~15;
      }
  
      av_log(ctx, AV_LOG_INFO, "cx: %d, cy: %d, cw: %d, ch: %d, rx: %d, ry: %d, edge: %d blocksize: %d contrast: %d search: %d\n",
             deshake->cx, deshake->cy, deshake->cw, deshake->ch,
             deshake->rx, deshake->ry, deshake->edge, deshake->blocksize * 2, deshake->contrast, deshake->search);
  
      return 0;
  }
  
  static int query_formats(AVFilterContext *ctx)
  {
      enum PixelFormat pix_fmts[] = {
          PIX_FMT_YUV420P,  PIX_FMT_YUV422P,  PIX_FMT_YUV444P,  PIX_FMT_YUV410P,
          PIX_FMT_YUV411P,  PIX_FMT_YUV440P,  PIX_FMT_YUVJ420P, PIX_FMT_YUVJ422P,
          PIX_FMT_YUVJ444P, PIX_FMT_YUVJ440P, PIX_FMT_NONE
      };
  
      avfilter_set_common_pixel_formats(ctx, avfilter_make_format_list(pix_fmts));
  
      return 0;
  }
  
  static int config_props(AVFilterLink *link)
  {
      DeshakeContext *deshake = link->dst->priv;
  
      deshake->ref = NULL;
      deshake->last.vector.x = 0;
      deshake->last.vector.y = 0;
      deshake->last.angle = 0;
      deshake->last.zoom = 0;
  
      deshake->avctx = avcodec_alloc_context3(NULL);
      dsputil_init(&deshake->c, deshake->avctx);
  
      return 0;
  }
  
  static av_cold void uninit(AVFilterContext *ctx)
  {
      DeshakeContext *deshake = ctx->priv;
  
      avfilter_unref_buffer(deshake->ref);
      if (deshake->fp)
          fclose(deshake->fp);
      avcodec_close(deshake->avctx);
      av_freep(&deshake->avctx);
  }
  
  static void end_frame(AVFilterLink *link)
  {
      DeshakeContext *deshake = link->dst->priv;
      AVFilterBufferRef *in  = link->cur_buf;
      AVFilterBufferRef *out = link->dst->outputs[0]->out_buf;
      Transform t = {{0},0}, orig = {{0},0};
      float matrix[9];
      float alpha = 2.0 / deshake->refcount;
      char tmp[256];
  
      if (deshake->cx < 0 || deshake->cy < 0 || deshake->cw < 0 || deshake->ch < 0) {
          // Find the most likely global motion for the current frame
          find_motion(deshake, (deshake->ref == NULL) ? in->data[0] : deshake->ref->data[0], in->data[0], link->w, link->h, in->linesize[0], &t);
      } else {
          uint8_t *src1 = (deshake->ref == NULL) ? in->data[0] : deshake->ref->data[0];
          uint8_t *src2 = in->data[0];
  
          deshake->cx = FFMIN(deshake->cx, link->w);
          deshake->cy = FFMIN(deshake->cy, link->h);
  
          if ((unsigned)deshake->cx + (unsigned)deshake->cw > link->w) deshake->cw = link->w - deshake->cx;
          if ((unsigned)deshake->cy + (unsigned)deshake->ch > link->h) deshake->ch = link->h - deshake->cy;
  
          // Quadword align right margin
          deshake->cw &= ~15;
  
          src1 += deshake->cy * in->linesize[0] + deshake->cx;
          src2 += deshake->cy * in->linesize[0] + deshake->cx;
  
          find_motion(deshake, src1, src2, deshake->cw, deshake->ch, in->linesize[0], &t);
      }
  
  
      // Copy transform so we can output it later to compare to the smoothed value
      orig.vector.x = t.vector.x;
      orig.vector.y = t.vector.y;
      orig.angle = t.angle;
      orig.zoom = t.zoom;
  
      // Generate a one-sided moving exponential average
      deshake->avg.vector.x = alpha * t.vector.x + (1.0 - alpha) * deshake->avg.vector.x;
      deshake->avg.vector.y = alpha * t.vector.y + (1.0 - alpha) * deshake->avg.vector.y;
      deshake->avg.angle = alpha * t.angle + (1.0 - alpha) * deshake->avg.angle;
      deshake->avg.zoom = alpha * t.zoom + (1.0 - alpha) * deshake->avg.zoom;
  
      // Remove the average from the current motion to detect the motion that
      // is not on purpose, just as jitter from bumping the camera
      t.vector.x -= deshake->avg.vector.x;
      t.vector.y -= deshake->avg.vector.y;
      t.angle -= deshake->avg.angle;
      t.zoom -= deshake->avg.zoom;
  
      // Invert the motion to undo it
      t.vector.x *= -1;
      t.vector.y *= -1;
      t.angle *= -1;
  
      // Write statistics to file
      if (deshake->fp) {
          snprintf(tmp, 256, "%f, %f, %f, %f, %f, %f, %f, %f, %f, %f, %f, %f\n", orig.vector.x, deshake->avg.vector.x, t.vector.x, orig.vector.y, deshake->avg.vector.y, t.vector.y, orig.angle, deshake->avg.angle, t.angle, orig.zoom, deshake->avg.zoom, t.zoom);
          fwrite(tmp, sizeof(char), strlen(tmp), deshake->fp);
      }
  
      // Turn relative current frame motion into absolute by adding it to the
      // last absolute motion
      t.vector.x += deshake->last.vector.x;
      t.vector.y += deshake->last.vector.y;
      t.angle += deshake->last.angle;
      t.zoom += deshake->last.zoom;
  
      // Shrink motion by 10% to keep things centered in the camera frame
      t.vector.x *= 0.9;
      t.vector.y *= 0.9;
      t.angle *= 0.9;
  
      // Store the last absolute motion information
      deshake->last.vector.x = t.vector.x;
      deshake->last.vector.y = t.vector.y;
      deshake->last.angle = t.angle;
      deshake->last.zoom = t.zoom;
  
      // Generate a luma transformation matrix
      avfilter_get_matrix(t.vector.x, t.vector.y, t.angle, 1.0 + t.zoom / 100.0, matrix);
  
      // Transform the luma plane
      avfilter_transform(in->data[0], out->data[0], in->linesize[0], out->linesize[0], link->w, link->h, matrix, INTERPOLATE_BILINEAR, deshake->edge);
  
      // Generate a chroma transformation matrix
      avfilter_get_matrix(t.vector.x / (link->w / CHROMA_WIDTH(link)), t.vector.y / (link->h / CHROMA_HEIGHT(link)), t.angle, 1.0 + t.zoom / 100.0, matrix);
  
      // Transform the chroma planes
      avfilter_transform(in->data[1], out->data[1], in->linesize[1], out->linesize[1], CHROMA_WIDTH(link), CHROMA_HEIGHT(link), matrix, INTERPOLATE_BILINEAR, deshake->edge);
      avfilter_transform(in->data[2], out->data[2], in->linesize[2], out->linesize[2], CHROMA_WIDTH(link), CHROMA_HEIGHT(link), matrix, INTERPOLATE_BILINEAR, deshake->edge);
  
      // Store the current frame as the reference frame for calculating the
      // motion of the next frame
      if (deshake->ref != NULL)
          avfilter_unref_buffer(deshake->ref);
  
      // Cleanup the old reference frame
      deshake->ref = in;
  
      // Draw the transformed frame information
      avfilter_draw_slice(link->dst->outputs[0], 0, link->h, 1);
      avfilter_end_frame(link->dst->outputs[0]);
      avfilter_unref_buffer(out);
  }
  
  static void draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
  {
  }
  
  AVFilter avfilter_vf_deshake = {
      .name      = "deshake",
      .description = NULL_IF_CONFIG_SMALL("Stabilize shaky video."),
  
      .priv_size = sizeof(DeshakeContext),
  
      .init = init,
      .uninit = uninit,
      .query_formats = query_formats,
  
      .inputs    = (const AVFilterPad[]) {{ .name       = "default",
                                      .type             = AVMEDIA_TYPE_VIDEO,
                                      .draw_slice       = draw_slice,
                                      .end_frame        = end_frame,
                                      .config_props     = config_props,
                                      .min_perms        = AV_PERM_READ, },
                                    { .name = NULL}},
  
      .outputs   = (const AVFilterPad[]) {{ .name       = "default",
                                      .type             = AVMEDIA_TYPE_VIDEO, },
                                    { .name = NULL}},
  };
  